Clinical and microbiological characteristics in predicting dentine caries progression

The purpose of this study was to evaluate the clinical aspect of dentine and its microbiota in predicting caries progression. The sample consisted of schoolchildren in the 7 to 14 years age group. Treatment involved cavity preparation trough the clinical criterion of hardness, with the collection of carious and remnants dentine for microbiological analysis. The clinical aspect (color and consistency) of the dentine remmants was recorded and the teeth were restored using silver amalgam and glass ionomer cement as pulpal protector (baseline - BL). After 1 year the restoration was removed and after new clinical and microbiological analyses, the teeth were then restored. Microbiological samples were collected at both time-points and cultivated in sheep blood agar, in anaerobiosis for 48 hours. Bacterial growth was analyzed quantitatively. Semiquantitative and qualitative analysis of the bacteria was performed by hybridization with genomic DNA probes and the checkerboard method. A significant difference was observed between the aspect of dentine remnants at BL and at 1 year (p=0.0078). The amount of bacteria at BL and at 1 year did not differ significantly (p= 0.37) and the microbiota of the carious dentine was predominantly composed of Gram-positive cocci. The removal of carious dentine based on the clinical criterion of hardness, followed by a well-adapted restoration, would determine the non-progression of caries. The few bacteria that still remained in the cavity would be no longer viable.